Stereoscopic gun sight having fixed oculars and objectives movable with the gun



June 24-, 1947. 5, ZAROODNY 2,422,710

STEREOS COPIC GUN SIGHT HAVING FIXED OCULARS AND OBJECTIVES MOVABLE WITH THE GUN Filed May 10, 1944 5 Sheets- Sheet 1 Fig. 1-

Serge LT- Znrumdry June 24-, 1947 s. J. ZARQODNY STEREOSCOPIC GUN SIGHT HAVING FIXED OCULARS AND OBJECTIVES MOVABLE WITH THE GUN Filed May 10, 1944 5 Sheets-Sheet 2 'June 24, 1947. s, ZAROODNY 2,422,710

STEREOSCOPIC GUN SIGHT HAVING FIXED OCULARS AND OBJECTIVES MOVABLE WITH THE GUN Filed May 10, 1944 5 Sheets-Sheet 5 EllE'IElE T T zufundr y June 24-, 1947. 5, J ZARQQDNY 2,422,710

STEREOSCOPIC GUN SIGHT HAVING FIXED OCULARS AND OBJECTIVES MOVABLE WITH THE GUN Filed May 10, 1944 5 Sheets-Sheet 4 ON THE TARGET Serge Tl- Z'nruudny June 24, 194-7. 5, J ZAROODNY 2,422,710

STEREOSCOPIC GUN SIGHT HAVING FIXED OCULARS AND OBJECTIVES MOVABLE WITH THE GUN Filed May 10, 1944 5 Sheets-Sheet 5 "IUU lava

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INFINITY A 0 3mm LEFT EYE RIGHT EYE v EIEP E LL-Znrncldry k A Patented June 24, 1947 STEREOSCOPIC GUN SIGHT HAVING FIXED OCULARS AND WITH THE GUN OBJECTIVES MOVABLE Serge John Zaroodny, Aberdeen, Md.

Application May 10, 1944, Serial N 0. 535,335

4 Claims.

(Granted under the act amended April 30,

l The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The invention relates to telescopic gunsights and particularly to stereoscopic sights, and has for an object to provide a simple sight of this nature applicable to general use on heavy caliber arms, but especially valuable for use in tanks with heavy armament. A paramount purpose is to reduce need for laying by observation of result of fire.

Heretofore there has been provided a peri-scopic arrangement including a simple reflecting system without magnification, for the left eye of the gunner, and a periscopic telescope for the right eye. No benefit of stereoscopic vision is thus possible, and while a reticle is included with certain graduations to aid in estimating range, monocular vision and uncertainty of adaptability of gunners to eifective use of the apparatus lowers efiectiveness of the weapon, to which it is applied.

There has been a serious obstacle to perfection of stereoscopic sight means for tanks in the fact that the gunner must remain at one side of the gun and maintain a fixed position of the head regardless of movements of the gun, owing to the confined space in the tank turret, and therefore, the sights heretofore have been mounted on the roof of the turret with a linkage to the gun to move the periscope proportionately to the elevational movements of the gun. This has resulted in varying the angle of parallax which has had to be mentally estimated and allowed for in laying the gun.

It is therefore an important object of the invention to meet these arbitrary requirements and at the same time enable complete stereoscopic vision with a novel function of reticle devices enabling instant correction of elevation for range without mental calculation on the part of the gunner. It i sought, too, to entirely eliminate parallactic angles between the gun axis and the line of sight.

A further desideratum in View is to enable the mounting of telescopic objectives on the gun, to move therewith, while preserving the fixed positions of the eye pieces of the sight in the turret, with a simple coupling liable in a minimum degree to impairment by wear, temperature changes,

of March 3, 1883, as

or shock. Also it is an aim to provide a novel linkage between objective and eye pieces which will not be easily deranged by removal and, replacement of the gun and will function effectively without tending to interfere with conventional training of the weapon, and its stabilization by automatic stabilizing devices.

An important improvement in view is to eliminate the need for openings in the turret armor near the gunner and particularly not in a foreand-aft line with the gunner.

It is a motive to preserve the capability of speed and simplicity in operations required to lay the gun, while coincidentally determining the range, but obviating the need for memorizing calibration values of markings on a reticle, to a large extent.

It is also sought to enable a satisfactory magnification of the target image and at the same time provide a reasonably large field of view, so that the requirements of rapid movement of armored units in combat can be met.

A still further object of the invention is to enable ready replacement of exposed parts of the optical system in such manner that ready maintenance of alignment and accuracy of the elements is made practicable.

In the attainment of the foregoing objective it is additionally a, purpose to make the sight rugged throughout so that there will be a minimum tendency to become impaired by the rough usage and shocks to which it will be exposed.

The need of improvement in these respects and others effected by my invention, becomes especially important when the situation of a tank gunner is considered. In addition to the fact that he is compelled to remain in a fixed position much to the right of the grui and also with his head at some distance labove, he must give attention to details requiring constant attention and immediate reaction which correspond to ordinary artillery service performed by several men.

Thus, while there is a captain included in the crew who has a panoramic observation post and assists to the extent of determining the general course of attack, and may at times instruct asto the particular target, he customarily also operates a .50 cal. machine gun and, the gunner must nevertheless select the target in the sight, often independently, and also must use initiative in n mir firing on more than one target where necessary, and at times without aid or orders of the captain, especially if the latter is disabled, as is likely to happen because of his exposed situation, or when a violet offensive action by an enemy makes observations by the captain inadvisable. ner must judge the range, instruct the gun loader as to what ammunition to use, note the servicing of the gun by the gun loader, watch the movements of the target to determine lead and elevation for corrected range, windage, and time of flight of the particular ammunition used, manipulate the controls by which traverse and elevation movements of the gun are effected, allow for parallax, and fire the gun. Other matters occuply his attention and require action, such as instruction to the driver and assistants. At th same time there is an accompaniment of noises both wthout and within the tank, high explosive detonation waves, and lurchings of the vehicle which tend to throw the gunner out of position and at times threaten bodily injury. In summer, or tropical situations, excessive heat is manifest. Accuracy of fire becomes more important, also, in consideration of the large caliber of the principal armament in these vehicles, and the cost and limited number of rounds which may be carried,

as well as increased threat from an enemy target by delay in efiective fire.

It is a salient aim of the invention to enable a stereoscopic range finder to be used as a direct sight.

Additional objects, advantages and features of invention reside in the construction arrangement and combination of parts involved in the embodiment of the invention, as will appear or be understood from the following description and accompanyingdrawings, wherein:

Fig. 1 is a fragmentary top view of a gun and stereoscopic sight installation in a tank;

Fig. 2 is a, vertical sectional view'of the system;

Fig. 3 is a diagrammatic view of the optical system of the sight;

Fig. l is a detail perspective view of the compensating mirror mounting and linkage between the moving and fixed parts of the optical system;

Fig. 5 is a detail vertical section of an objective-reticle unit;

Fig. 6 is a cross sectionthereof at the mounting bracket;

Fig, 7 is a horizontal section of the right eye piece and telescope box, the left one being shown in plan.

i s. 8 and 9 are details of the left and right reticles and a target as seen in the respective eye pieces;

Fig. 10 is a representation of the field of view with the images of the reticles superimposed sterescopically, the gaze not directed to the target, but to infinity;

11 is a similar view illustrating the appearance of the combined images when indicating an over-range over or beyond the target due to failure to coordinate stereoscopic use of the eyes with the actual distance of the tar-get, or an error in selecting the actual point of intersection of the reticle ima es :7

Fig. 12 is a similar View indicating a short which woul cause the projectile fired in accordance therewith to fall short of. the target, an error due to. same personnel: faults as the erro of Bio. 11;

Big. 1315 a similar view showing how the. correct. range is; effected by aligning the intersection or the two reticle patterns by correct stereoscopic The gun- V use of the eyes in accordance with the actual distance of the target, and correct estimation or observation of the intersection.

Fig. 14 is a schematic view, showing the functioning of the eyes of an observer with the reticles, fictitiously but illustrating the principle on which the invention functions;

Fig. 15 is a view of the stadia figure observed at minimum range observation.

The telescopic system of this invention includes two objective units (in which reticle and collector lenses are also included) at respective sides of the gun and fixed thereto, and a separate stationary projection system for each objective unit,

axis is defined by lateral trunoions 25- carried by the turret structure, the elements of which are fixed with the turret, excepting for such occasional adjustments as may be required. The stationary system is optically coupled with the objective unit by a reflector device, which transmits the incident light from the objective constantly on the axis of the stationary system, throughout movement of the objective with the gun.

Referring more particularly to the drawings, there is illustrated a portion of a tank turret 28, including a roof portion 2!, a front wall 22 having a gun port 23 on which a bulge plate or cover 24 is secured concentric with the horizontal pivot axis of a gun 25, the latter being conventionally constructed, mounted and operated. This pivot fixed on the cradle 2'! of the gun. In the bulge plate 24 a vertical slot 28 is formed through which the gun projects and in which it is depressible from the normal horizontal or Zero position shown in Fig. 2 over an arc of about ten degrees and elevatable from zero over an arc of about twenty-five degrees. The tank construction may be conventional or of any improved construction. The turret may have the usual mounting, basket structure, and equipment and the gun may include any preferred breech construction and mechanism, including a firing means preferably foot operated as heretofore all these features being known and well understood, for which reason they are not illustrated. As is known, in these installations azimuth tracking or traverse of the gun is usually effected by a power drive rotation of the turret, controlled by a simple lever operated manually by the gunner. It is usual to provide a stationary gunners seat at the right hand side of the gun slightly forward of the breech and below, without any provision for rocking or other movement relative to the turret, while a captains seat is usually provided slightly above the breech with a hatch thereover, and another seat rearwardly of the gunners seat, these being factors in determining the location of the telescopic sights although not here illustrated, the structure being well known.

A heavy armor shield not shown spaced forwardly from the plate 24 receiving the gun therethrough extending laterally on each side of the guna short distance beyond the slot 28-, and extending above the gun a distance slightly more than that extent of the slot which is exposed when the gun is at the lower limit of movement on the trunnions, and the shield also extends downward a distance below the gun.

The gun cradle 27 carries recoil cylinders 3!! and the trunnions are extended on each side of the cradle outwardly of these cylinders, to usual bearings 31. However, these bearings are spaced outwardly sufficiently to permit telescopic elements to be located on the side of the cradle and in or inwardly of the trunnion, as will be described. The right hand trunnion may also be extended as at 32, axially beyond the bearing to accommodate elevating gearing not shown, but which may conform to any preferred practice.

The inner part of each trunnion is formed with a large recess 33 open at the upper and rear part, extending over a suitable radius beginning near the lower horizontal tangent of the trunnion periphery. The recess includes substantial space forwardly of and below the axis of the trunnion.

On each side of the cradle forwardly of and slightly above the trunnion an objective mount bracket 34 is provided on the side of the cradle. A slide 34 is vertically movable in guides 35' mounted on the bracket 34. See Figs. 2, 5 and 6.

The slide is vertically adjustable by means of a fooussing screw 35 having a collar 35 held between plates 3'l38 mounted removably by screws 39 across the upper ends of the guides, the screw being engaged in a tapped and threaded boss on the slide. The upper end of the screw 35 is slotted for rotation by a screw driver, and may be exposed (by depressing the gun) with the screws 39, under a sight slot 40 formed in the bulge plate 24 in a plane alined with the objective unit to be described. Access may be had to the screw 35 from within the turret by elevating the gun to the maximum. The top plate 38 has a middle part offset upward less than the thickness of the collar 36 and apertured to receive therethrough the reduced head of the screw 35. Thus, when the screws 39 are screwed home the focussing screw is secured against rotation. The bracket and plates 3'l-38 may be removed as a unit by loosening the screws 39.

The slide 34' is provided with a horizontal cylindrical collar 4! through which there is slidably and rotatably engaged an objective lens 43 and at its rear an L fitting 44 in which reflector prism 65 is mounted. the reflecting axis in this instance being at an angle of forty-five degrees to the axis of the lens. the prism being retained on a suitable seat in the L by a cover can as and cork ring. This fitting has a short downward extension 41, against which a combined reticle and collector lens 48 at the right unit and 49 at the left unit is retained by a ring 50 screwed on to the extension ll. The barrel is secured in its longitudinal and rotative adjustment by a set screw 5| engaged through the upper side of the collar 4!.

The barrel is of a length to extend to or near the sight slot 40, while the reticle is axially disposed on a radius of the axis of the gun trunnion. In the present instance, the axis of the reticle is at right angles to the axis of the objective, but the angle of reflection may be oblique to the objective axis and the reticle and collector lenses likewise rearranged-the fitting 46 being correspondingly modifiedwhich will permit the unit to be positioned further forward on a different radius of the trunnion axis. A greater elevation of the gun with constant optical coupling of the objective unit and eye pieces might then be effected, as will be understood. Such variation of angle, being readily carried out, is not here illustrated. The base represented by the distance between the objectives may be increased if desired, with appropriate modification of the trunnion arrangements, as for instance, by locating the objective units outwardly of the bearings of the trunnions. and other appropriate corrections made as will be understood hereinafter.

A number of objective optical units 42 may be carried in the tank as spares for replacement of units damaged, as may occur by enemy fire or otherwise. By reason of the fixed focal relation of the lenses in this unit, replacement may beeffected without disturbing or requiring rearrangement or modification of the stationary system. The adjustment by screw 35 will ordinarily not require changing, but its adjustment might be required if a slight displacement of material of the front wall of the turret should occur,

as, by a direct hit by a high explosive projectile.

or bomb, which might not be sufficiently effective to put the tank armament out of action.

The stationary system may consist of a series of lenses and reflectors and eye pieces without connecting tubes or barrels substantially as indicated in Fig. 3, but is shown in Figs. 1 and 2 as having suitable barrel connections so that the optical path of the sight will be less likely to be interrupted. Identical receiver tubes 52 are fixedly mounted on the turret at respective sides of the gun each in a plane with the axis of the respective objective unit and with its axis coincident with some convenient rearwardly inclined radial plane of the trunnion axis. These tubes are thus parallel and adapted to function with identical objective units if emergency should require.

A mirror 53 is mounted in the recess of each trunnion with a mounting 54 pivoted on the axis of the trunnion and with the mirror in a plane coincident with the axis but movable independently of the trunnion. The mounting has fixed thereon a rigid rectilinear rod 55, which, for convenience in illustration and understanding of the invention, is at one side of the mount and normal to the plane of the mirror, and radial to the pivot axis of the mirror. A sliding block 56 is bored to receive the rod therethrough and i engaged slidably thereon. Two links, 51 and 58, of the same length, are mutually pivoted on the block, and, when the mirror is at its most forward position, the block is positioned at an inner part of the rod with the links extended at equal angles to the rod, the link 5'! being extended forwardly and connected at its extremity to a pivot pin 59 set on the trunnion, while the link 58 is extended rearwardly arid pivoted on some member fixed in relation to the turret, in the present instance a bracket arm 60 carried by a collar 6| secured around the end portion of the tube 52, the bracket being rearwardly of the tube and bowed rearwardly so as to afford a clearance for full rearward movement of the fitting 44 under maximum elevation of the gun. The tube 52 stops short of the arc described by the upper part of the cap 46 of the objective unit under maximum elevation of the gun, so that the fitting 44 may move across the axis of the tube 52 at times, optical coupling being then interrupted between objective and the stationary system in the particular device illustrated, but attention is directed to the simple expedient before mentioned for avoiding early interruption in such movement. The maximum elevation of the gun is customarily twenty-five degrees above horizontal and depression ten degrees below horizontal.

Due to the facts that elevation above ten or fifteen degrees is exceptional, and that when greater elevations are used it is likely that range finding and elevation computation will be desirable (often incident to firing on a target not visible at the gun), it may be found, sufilcient to provide for optical coupling within much less than the maximum range of movement in elevation, allowing the fitting 44 to move across the axis of the tube 52 at the greater elevations, as here shown.

At the upper ends of the tubes 52 mirrors 62 are mounted arranged to reflect incident light laterally toward the right hand side of the turret through a long cross-tube 63 from the left hand tube 52, and through a short cross tube 64 for the right hand tube 52. The last mentioned cross tube stops nearer the right hand side of the turret, where a right hand box 65 is mounted in which there is a reflector assembly including three mirrors 66, 61, 58, the first reflecting the rays from the tube E l to the upper forward mirror 61, which reflects them forwardly and downwardly to a pivoted interpupillary compensator mirror 68 forwardly of .and above the mirror 66 and positioned so as to throw the incident light rearwardly to the eye lenses 69 for the right eye.

A somewhat similar box and reflector assembly may be provided at the right hand end of the long cross tube 63, cooperatively associated with the left eye lenses 1|, although a simplification of the mirror system may be effected if desired and the mirror corresponding to the one 68 need not be pivoted. The left eye lenses are mounted at the rear part of a'stationary tube 12 extended integrally from the box 10 and located adjacent to, or connected to, a head rest 13, which extends to the right and past the eye lenses 69 which are laterally movable. The right eye lenses 69 are mounted in a right tube 14, stopping at, and separate from, the box 65; which has a vertical rear side 15 formed with a port 16 transversely enlarged toward the right, of suflicient size to pass the light representing the field projected to this point, as will be described. The tube 14 is provided with lateral planiform flanges 17 arranged close to the rear side of the box 65, to close the port 16 when the tube is displaced laterally to either extreme of position at this port, and the box is also provided with'lateral flanges 13 parallel to the flanges 11 and cooperating therewith to prevent access of extraneous light. In addition, a boxing of flanges 19 is provided across the plane of the joint between the forward end of the tube 14 and rear end surfaces of the box. The flanged end of the eye tube 14 is laterally reciprocable in this boxing.

The tube 14 is supported in horizontal alignment with the port 16 by the boxing 19 and in the head rest 13, and in part b means of two parallel links 89, both of the same length, one pivoted on the under side of the tube 14 on a vertical axis, which, at the inner limit of adjust ment of the tube 19, intersects the axis of the lens 69; and the other pivoted on a laterally extended bottom plate or flange Bl on the under side of the tube, the two links being extended forwardly, offset downwardly and pivoted the one on the under side of the box 65 and the other on a lateral ear 82 extended from the box. The rear extremity of the tube 14 may be supported by a flange 83 formed as part of the head rest 13. The tube 14 is thus transversely reciprocable, the links maintaining it always parallel to the tube 12.

The head rest is formed with a horizontally elongated right eye port 84, of sufficient dimension to accommodate the full fourteen millimeters of adjustment of the lenses 69 between the minimum and maximum interpupillary measurements (72 mm.) of men accepted for gunnery; and the tube M is provided with wings 85 at each side 8 to close that part of the port 84 beyond the eye piece at either side. The rear end of the box 65 and the forward end of the tube 14 may be inclined slightly forward toward the right, so as to allow for the slight longitudinal displacement of the tube due to the are described by the links 80.

The compensating mirror 68 is set in a mount 35 suitably inclined for the reflective function required, but pivoted on a vertical axis on the box 55, including a depending shaft 81 extending below the lower part of the box and having fixed thereon an arm 88, which, when the mirror is properl positioned on its axis to reflect a beam or pencil of light axially to the eye lenses 69 (as shown in solid lines in Figs. 1, 2 and 7), is aligned with the adjacent link and pivoted thereon intermediately the length of the latter. A perpendicular of the mirror 88 radial to the shaft 81 will thus bisect the horizontal angle formed by axial incident and reflected rays of the field at this mirror when the tube [4 i laterally adjusted; and the reflected ray will be thrown to the center of the lenses 69 at all positions of the tube 1 3. The tube 14 and mirror 68 may be secured in adjusted positions by a thumb nut 81' on the upper end of the shaft 81 clamping the same to the top of the box 65.

At the objective unit the lens 48 may be of sufficient focal length to equal somewhat more than the distance to the compensating reflector 53 and up to the reflector 62 at the upper end of the tube 52, or the lens 48 may be a collimator; and in the cross tube 84 or elsewhere, inverting lenses of appropriate focus or inverting prisms may be mounted, adapted to bring the field image to the right eye lenses in a conventional manner. In the long cross tube 63, lenses of correspondingly longer focus if required, or other system matched with the right hand system, may be mounted, functioning in like relation to the left eye lenses. The stationary optical systems for each eye may conform to practices in transmitting images through periscope devices. The lenses in the longer path to the left eye may be of larger diameter if desired, in order to avoid making the image at the left eye noticeably less bright than that at the right eye, this being a conventional expedient not illustrated.

.Any usual means for adjusting the device to individual dioptic requirements may be included, and in order to compensate for possible disturbance of the erect positions of the two images by battle shocks or otherwise. Swasey or Amici prisms or other devices may be included for making appropriate corrections of this kind.

Any approved closure for the space around and between the rear end of the objective unit and the adjacent end of the tube 52, may be employed.

Alternative arrangements and construction of the lenses and reflectors will occur to those versed in the art and may be substituted or incorporated as preference or expediency may dictate. Thus, by forming the collector lens, 48 as a collimating lens duplicate erecting devices may be used in both right and left optical systems, the lens in the left eye system being simply positioned further to the right from the reflector 62, than in the system for the right eye.

The reticle patterns at the collector lens 48 may if desired conform to developed practices and the general function of a stereoscopic telescope system is well understood. However, in the present instance, owing to the exigencies of the service involved, and requirements of the particular embodiment of the system presented, an

improved reticle is provided in which right and left patterns or figures B9, 89" are formed, respectively, on the right and left reticles, as shown in Figs. 9 and 8. The pattern in each reticle consists of a series of spaced dots as illustrated, although each item or dot may consist of a small ring, a short line, or both a horizontal and a vertical line these expedients being obvious and therefore not illustrated. Each pattern is in the form of a series arranged on a parabolically curved line one end of which starts at the lower edge in each reticle immediately adjacent, and with a minimum slight spacing from the vertical diameter or axis of the reticle, the curve in the right reticle extending upwardly curving toward the left from a point immediately to the left of the vertical axis and recurving slightly downward toward the left, terminating at the periphery of the reticle, this latter intersection depending on the dimensions of the parabola. This curve will be related to the trajectory of a projectile, and a particular ammunition allowance may be included in the pattern by using cross lines of lengths related to given rounds, and may be varied to suit the ammunition used. The dots in the present instance are varied in spacing, the intervals being progressively decreased from the lateral end or bore 9| in each reticle to the lower extremity of the series. Other spacing may be followed, however. In the left reticle the figure is reversed in form and position, but is in the same relation to the axes of the reticle, the line of dots curved in the opposite direction from that of the curve in the right reticle, that is, toward the right from near the vertical axis of the lower edge of the reticle, and of identical form, size and number of dots. The vertex of the curve in each reticle is adjacent but below the horizontal diameter of the reticle and its lateral extremity is a distance further below.

The parabolic curve is not necessarily shaped to correspond to a particular trajectory curve, but conveniently to a range scale representing the points of intersection of the two figures which will occur at corresponding dots when the observer focusses his gaze on a target image in the sight at respective distances. The curve may be, howeverand preferably is-in such shape and proportions as to correspond to the trajectories involved for a target or targets on the same horizontal plane, or the same plane with the base of the mount vehicle, to function as below described.

In use, the system being constructed and assembled as described, when the gun is horizontal, the horizontal diametrical line in the field seen when the observer gazes into the eye pieces will correspond closely to the horizon, the reticle pattern seen when the gaze is focussed at infinity in the manner illustrated in Fig. 14, will be approximately as shown in Fig. 10. Should a target 90 be in the field of View say in the left lower quarter, it will appear for instance as in Figs. 8 and 9 in the left and right telescopes, and the stereoscopic field will appear substantially as in Fig. 10 without the observer fixing his attention on the target. However, when the target is at an intermediate range distance, and the observer focusses his eyes thereon, the convergent movement of the eyes will cause the two halves of the reticle image of Fig. 10 to apparently move translatively inwardly, and the parabolic lines of the figures 89-89 will appear to intersect, at apoint distant from the bases 9| of the figures proportionate to the actual distance of the target. Those two dots located at or nearest the point of intersection will appear as one and will have that range value in meters or yards. The values for the whole series may be memorized if desired to satisfy the wish of the observer for specific information of the kind, although not required in the aiming of the gun in most instances.

When the observer has thus efiected an apparent intersection of the combined reticle figures, the result may be considered equivalent to, or actual stereoscopic contact such as is effected in stereoscopic range and height finders, where, by rotation of wedges, the image and the reticle symbol are made to appear in the same distance phase. At this point of functioning of the gunner and sight, the gunner has not given special attention to the stadia or reticle figure or symbol, having only focussed his gaze on the target. But he will perceive the point of intersection of the lines subconsciously and simultaneously. Henow consciously notes quickly the dots in the series where the intersection occurs, applying his gaze to this intersection, which may appear as one dot, and by maintaining his attention on this point the dots of the combined figures at the intersection will remain merged as one.

If the target is on the same'horizontal or nearly horizontal plane as the vehicle, the gunner now manipulates the azimuth and elevation controls so as to swing the gun, causing relative movement of thetarget image so that these merged dots coincide with the target as in Fig. 13. The gun will then have the necessary elevation to give the range desired, using standard ammunition. Compensation for lead may be effected convention.- ally. Should a difierent ammunition be required or used, a distinct series of marks on different curves may be included on the reticle or a different reticle used, to enable such alternative ammunition to be used; or other indicia used, related to the range requirements at the distance indicated, or a compensation reckoned by the gunner.

If, however, the observer, after noting the intersection mentioned makes an error, as for instance selecting dots an interval too low, and fixes his attention thereon, the figure will appear as in Fig. 11 and the elevation of the gun will be excessive, the projectile falling beyond the target, producing an over when trained as described and fired. Likewise, if dots an interval too high or too far toward the bases 9| on the reticle symbol are selected, as Fig. 12, the elevation will be insufiicient and the projectile fired will fall short of the target.

In addition to the sighting and aiming described the gunner may have to make allowances for lead on moving targets, and windage, which may be done conventionally, or by newly devised apparatus or without mathematical procedure. In such cases the gun is trained on the target so as to learn the range by the nature of the intersection produced as described, after which the displacement from the coinciding relation of merged dots and target, may be made, proportionate to the correction required. If quickly responsive means for operating range-compensating and lead compensating wedges or other deflectional devices are available for moving the target image relative to the reticle, o shifting the reticle or stadia image on the field of view, these may be incorporated in my sight.

It has been contemplated to provide an extension of theelevation and azimuth controls to a place near the captains seat, so that in case of severe jolting or lurching of the tank if the gunner loses sight of the target and is unable to resume tracking promptly, the captain, with wider View, could quickly bring the target again into the gunners field of vision. The latter feature however comprises no part of the present invention, and therefore is not shown, but it illustrates the recognition of the fact that an auxiliary observer has a place in the aiming of the piece in this situation.

Simple mirrors have been shown at several points of angular diversion of the light from the objective, but prism elements may be designed and substituted Where considered desirable. It is'c'onsidered possible that a penta prism may be found advantageous in place of the one 45.

It should be'noted that the objective unit is sealed by the lens 43 at the forward end, and by the lens-reticle 48 at the rear end, as well as by the cap plate 45, so that there is a minimum liability of access of dust or dampness to the interior of this unit.

It should be understood that as the telescopes are elevated, the image of the target is lowered in the field of View, and consequently the lower inner parts of'figures represent elevation increasing directly as the spacing of these from the horizontal diameter of the field.

The reason the lines of the reticle figures curve downward at their upper lateral parts is, that after a target approaches within a certain range further depression of the gun would tend to throw projectiles too low and it is desirable at the minimum'ranges to elevate the gun so as to be more effective on target superstructure such as enemy tank turrets, buildings, etc, This lateral curvature may be varied or flattened as experience or developed practice may indicate to be desirable.

The spacing of the dots in the figure of one reticle is identical with the spacing of dots in the figure on the other reticle, and dots of a given order in one reticle are horizontally aligned with those of like order in the other reticle, and similarlyspaced from the vertical axial plane of the objective, so that under stereoscopic f ocussing movements of the eyes the corresponding dots of the reticles are caused to register with each other according to the degree of convergence of the gaze of the two eyes.

As in the case of conventional reticles, the present stadia figure appears to be floating in space and the curves suggest to the observer a projectile trajectory, this becoming more effec tive when the attention is fixed on thetarget. The dots thusappear to be spaced further from the observer as they are positioned relatively lower (in the'inner part of the combined figure as in Fig. 13 for more distant targets, and the lower outer part for near objects) as in Fig. 15. The idea is to make one dot, for instance, appear to be floating in space at a distance ofsay yards, andlanother'adjacent the first one, appear to be at a distance of 1 100 yards and when two dots in the figure are caused to merge this apparent distance value is preserved although the gunner may not at once, or ever; associate. such numerical values with the figure in the rapid operation of th gun and sight.

The telescopic field will include an angle much less than the total scope or angle of movement of which the gun is capable, but the full scale of ranges for the entire possible elevational movement do not have to be included in the reticles or field of vision of the telescope. This enables the use of a scaleof few divisions as inthe particular scale shown, or any other, because the training movements of thegun which will keep a given target Within view, require small total angular movement of the gun to reach the extremes of average range after stereoscopic contact. In many instances part of the necessary movement will have already been accomplished in bringing the target into view.

The curve on which the lines of the reticles are laid i such that the spacing of any two dots of like order in the series of the superposed or registered reticles will represent the difference between the parallel axes of the eyes of the observer when gazing at infinity, and the intersection of the convergent axes of the eyes when gazing at a target located at a distance corresponding to the range value assigned to the dots involved. In consequence, such two dots will coincide when the vision of the gunner is focussed on a target at such distance appearing in the sight. This principle governs the form and location of the. curve in the figure in each reticle throughout.

After the adjustment of the eye piece for increased interpupillary distance, it will be observed that the axis of the eyes when gazing at infinity in the instrument shown will be slightly convergent, but this will not change the relative axial changes due to focussing upon nearer objects, and th -same stereoscopic efiects and range functions will be manifest as described. There is an advantage in the initial convergence in, that stereoscopic adjustment of the observers eyes is made easier, psychologically and physically, since it is usually easier for a person to look crosseyed than to move the eyes divergently.

While in the present instance thereti cle figures are shown as formed below the horizontal diam-" eter of the field of View projected this is due to the objective unit axis being in a plane with the bore axis. The latter relation is, not arbitrary and th two objectives may be somewhat depressed below the bore axis so that when the gun is horizontal the telescope objective is somewhat depressed. This would bring the horizon above the horizontal axis of; the field o f view, presenting less sky and-more foreground to view In consequence, a greater elevationof the piece is possible while keeping the targetin View; permitting also a greater vertical extent of thereticle figures and greater ranges inpludable.

The curved series offigures in the reticles may be utilized in various forms other than the ones shown, and; may extend above the horizontal diameterof; the field or above the line representing the ho i on, i on thou de ss on. of h telescope objective units as last mentioned. In cas the series extends above the horizon line, r, a ov e h z n i me erof hefidd f W th ut pr ss qn of the b cti e. the pper d v ge t por io s of t e s e may be i ized s e s o ca ly befo e n cated, o det m n n e hut e sun wou d e evate Without referenceto' the level; of; the retiele. line e e io Ales t is not. es entia t at; the uppe a e al e d. p rt 1 ofth u ved; e ies bev curved downward, but the curve may have a continuous ascendant form to its lateral termination, lt-isgbelieved preferable, however,- for the functional valuesv described, to have it in a a q orm-V o t m t has be n m de to. epresen an exact aa a nof e ret c e s al euresshown in F r 8 9 o a pa i u ar instrum nt thesebeingexemplaryor fictitious andsubject to production in accordance with the base line th. J st e e en he t ve and;

the actual difi'erencesin the .anglessubtended magnification, as well as preferences as to stereoscopic training and other practices.

The principle on which the reticles are utilized is illustrated in Fig. 14, where the two eyes of the observer (with an exaggerated interpupillary distance) are represented at 92 and the reticles shown in coaxial relation correspondingly enlarged, but relatively much nearer the eyes than in actual practice. It may be seen that when gaging at infinity the axis of vision of the two eyes lie outwardly of reticles which produces the figure of Fig. 10, as the eyes become directed to nearer objects, the convergence of their axes causes them to intersect the reticle figure, further from the vertical axis of the field, beginning with the lowermost dots, and as an object at minimum range is observed, dots nearer the bases 95' will coincide, until at lowest range the extremities Qi themselves may be registered, as in Fig. 15. A scale of yards has been marked in Fig. 14 simply to illustrate the principle, but the actual embodiment may be of different values and form. The convergence of the axes of vision for the ranges has been greatly exaggerated in Figure 14. In Fig. 15, also the use of other forms of marks on the reticles is indicated, short diagonal lines being indicated having an inclination in one reticle in a direction opposite the direction of inclination of the lines of the other reticle, so that when marks of the two coincide a cross is produced in the stadia figure. It may be seen, however, that the intersection of such lines will occur over a substantial angle of coincidence or lap of the reticle figures, and it is thought that dots will reduce uncertainty as to the exact range indicated, a1- though some observers may be able to determine the values of various intersection positions of the same two marks of Fig. 15.

It is also possible to use horizontal lines on one or both reticles, or on one while vertical lines are used in the other. The horizontal lines may be varied progressively in length in proportion to the ranges indicated and to an average speed of a target, so that compensation for lead would be indicated. For example, such lines where horizontal may have such length that the shell would hit a target travelling laterally at 30 miles per hour and (as seen in the telescope) entering the horizontal line indicating the proper range at the instant of the shot. The vertical lines may indicate ammunition values, different from that for which the horizontal lines are designed, so that allowances may be readily indicated at the moment.

The subject matter just described in connection with Figs. 8 to 15, inclusive, is claimed in my copending application, Serial Number 727,985, filed February 12, 1947.

Having disclosed my invention in the best form in which I have developed it, and with the understanding that this is purely exemplary and subject to improvements and corrections which will occur to those versed in the arts involved, including construction, rearrangements, substitution of materials and equivalents, mechanical and otherwise, without departing from the spirit of the invention, except as may be specifically excluded in the appended claims wherein:

I claim:

1. In a stereoscopic system of the character described, a support, a gun pivoted thereon for elevation and depression, a pair of parallel telescopic objectives arranged at respective sides of and on axes in respective vertical planes parallel with the bore axis of the gun, a pair of stationary eye lenses axially fixed relative to said support with mutual interpupillary spacing, and also spaced as a unit both in the same direction laterally from the vertical plane of the gun axis, their axes parallel to said plane, and right and left optical coupling systems between the objective elements and said eye lenses each including a compensating movable optical reflector coupling mechanically connected between the gun and support responsive to pivotal movement of the gun and objective relative to the support to maintain alignment of reflected rays with a given axis fixed in relation to the support extending generally upward beside the gun, a reflector means positioned to intercept the rays projected along one said fixed axis at a level above the gun and project the same transversely across said plane and beyond, means to intercept and deflect the transversely projected rays in optical coupling relation with the nearer of said eye lenses, and means to intercept and deflect the rays projected along the other said fixed axis in optical coupling relation with the other of said eye lenses.

2. In a telescopic sight of the character described, an objective unit consisting of a sealed tube having a forward rectilinear portion, an objective lens fixed coaxially therein, a reticle and collector lens fixed in the rear end thereof, a distant optical coupling system in receiving relation to refracted rays from the said unit including terminal eye lenses, and means to mount said unit on a gun consisting of a vertical guide on the gun, said collector and reticle having an axis at an angle to that of the objective, said unit having a mount part slidable in the guide, said tube being longitudinally slidable in the mount transverse to the guide, and means to secure the said mount part and tube in adjusted positions.

3. The structure of claim 1 wherein the gun has pivot trunnions revoluble on said support, said trunnions having recesses therein open rearwardly, said compensating reflector being pivoted on the trunnion in said recess for independent movement on the axis of the trunnion,

4. In a turret gun installation wherein the gunner points and fires an automatic gun from a confined position beside the gun and forwardly of the breech, a traversable gun support turret having a roof, a gun pivoted thereon for elevation and depression, a pair of horizontally aligned telescopic objectives arranged at opposite sides of the gun on axes in respective vertical planes close to and parallel with the bore axis of the gun, a pair of horizontally aligned eye lenses fixed to aid roof at the right of the gun and forwardly of the gun breech, both on axes parallel to and spaced in the same direction from the vertical plane of the gun axis, and right and left optical coupling systems between the objectives and said eye lenses, each including a compensating movable optical reflector mechanically connected between the gun and support responsive to pivotal movement of the gun relative to the support to maintain alignment of the reflected rays with a given axis fixed with the support extending generally upward beside the gun, a deflector means positioned to intercept the rays projected along the left said given axis at a level above the gun and to project the same transversely across said vertical plane and beyond, means to intercept and deflect said transversely projected rays in optical coupling relation with the said left ey lens, and means to intercept and deflect the rays from the other said given axis in optical coupling relation 15 with the right eye lens, said left optical couplmg system including a lens component of compensating greater focal length than corresponding parts in the right optical coupling system.

SERGE JOHN ZAROODNY.

REFERENCES CITED The following references are of record in the me of this patent:

UNITED STATES PATENTS Number Name Date 802,929 Forbes Oct. 24, 1905 2,354,153 St'ebbins 1 July 18, 1944 1,107,503 Eppenstein et a1. Aug. 18, 1914 1,869,530 1 Von Hofe et a1. 1 Aug. 2, 1932 1,864,899 French June 28, 1932 934,916 Von Hofe 1- Sept. 21, 1909 2,342,843 Corte et a1. Feb. 29; 1944 Number N ui'nber Name D te Ko'nig Feb. 1, 1910 Storer 1 Apr. 13, 1943 Radford Mar. 24, 1925 Gregory Mar. 17, 1942 Grub Sept. 24, 1901 'Gr'unber'g Aug. 2, 1932 Hayes Sept. 13, 1932 Klemperer Sept. 19', 1944 Jones 1 Dec. 13, 1932 Klem'perer Nov. 30, 1943 Schneider Dec. 28, 1920 Perrin et 21'. Nov. 23, 1926 Henderson Jan. 6, 1920 CI'eary 1 May 31, 1910 FOREIGN 7 PATENTFS Country Date Great Britain June 4, 1936 

